With the development of science and technology, people have increasingly high requirements for speakers, particularly, for mobile phone speakers, required are not only small size and sound, but also both small size and good tone quality are required. The tone quality is related to each link of the design and manufacturing process of a speaker, particularly, to the size of the rear cavity of the speaker. Generally, if the rear cavity of the speaker is reduced, the response to low bands is obviously reduced, and the tone quality becomes worse, so it is difficult to provide good tone quality in the presence of a very small rear cavity.
The above technical problem is generally solved by adopting the following several methods: first, replacing air in the rear cavity with gas having better acoustic compliance; second, filling the rear cavity with foam like melamine to increase the acoustic compliance; and last, filling the rear cavity with a porous material such as active carbon, zeolite, silica and the like to increase the volume of the virtual rear cavity and improve the acoustic compliance. The effect of the third method is most obvious, the zeolite filled in the rear cavity at present mainly includes FER, MFI and BEA structured molecular sieves, and MEL structured molecular sieves have not been reported.
Therefore, it is necessary to provide the present disclosure to overcome the aforesaid problems.